<!DOCTYPE html> 
<html lang="en"> 
<head> 
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width,initial-scale=1.0" charset="UTF-8" />
    <title>缓存全局变量</title> 
</head> 
<body>
    <input type="button" value="btn" id="btn1">
    <input type="button" value="btn" id="btn2">
    <input type="button" value="btn" id="btn3">
    <input type="button" value="btn" id="btn4">
    <p>1111</p>
    <input type="button" value="btn" id="btn5">
    <input type="button" value="btn" id="btn6">
    <p>222</p>
    <input type="button" value="btn" id="btn7">
    <input type="button" value="btn" id="btn8">
    <p>333</p>
    <input type="button" value="btn" id="btn9">
    <input type="button" value="btn" id="btn10">
<script type="text/javascript">
    function getBtn(){
        let oBtn1 = document.getElementById('btn1')
        let oBtn3 = document.getElementById('btn3')
        let oBtn5 = document.getElementById('btn5')
        let oBtn7 = document.getElementById('btn7')
        let oBtn9 = document.getElementById('btn9')
    }

    function getBtn2(){
        let obj = document
        let oBtn1 = obj.getElementById('btn1')
        let oBtn3 = obj.getElementById('btn3')
        let oBtn5 = obj.getElementById('btn5')
        let oBtn7 = obj.getElementById('btn7')
        let oBtn9 = obj.getElementById('btn9')
    }
</script> 
</body> 
</html>